Objectives. At the present time, amplitude-phase shift keyed (APSK) signals are actively used in satellite communication systems. In particular, they are applied in systems which operate in a limited radio frequency spectrum with increased data transmission quality requirements. Such systems use multi-channel type receivers with maximum likelihood decision on the received symbol (correlation receiver) or quadrature type receivers. The noise immunity of these receivers is directly dependent on the quality of the formation of reference oscillations. These oscillations are reference signals for correlation receivers and in-phase and quadrature components for quadrature receivers. The aim of the work is to analyze the influence of the amplitude and phase parameter spread of the in-phase and quadrature channels on the noise immunity of receiving APSK signals with a circular shape of the signal constellation. Methods. Methods of statistical radio engineering, theory of optimal signal reception, and computer simulation are used. Results. The study established the characteristics of noise immunity of the APSK signal reception depending on the spread of parameters of the quadrature converter. The theoretical calculations were confirmed by the results of modeling the transmission of APSK signals in a Gaussian communication channel. A comparison with systems using quadrature amplitude modulation (QAM) was carried out, in order to assess system stability in the presence of spread parameters among other similar systems. Conclusions. The studies enabled us to conclude that an imbalance of the quadrature reference oscillations can lead to a significant decrease in the noise immunity of radio systems using APSK signals. The minimum energy loss due to imbalance of quadrature reference oscillations is achieved when the imbalance value is less than 10% in amplitude and 2°–3° in phase. The amplitude imbalance of quadrature reference oscillations when receiving QAM signals is more pronounced than in the case of APSK signals. The phase imbalance affects approximately the same.

Objectives. Radio engineering information transmission systems are widely used in robotic systems employed in various military and civilian services. If such systems are used in a harsh environment, where a large amount of retransmitted interference occurs, for example, if a complex is buried under rubble or is located in reinforced concrete pipes or other utility facilities, communication with the command post may be lost. Thus, the task of maintaining reliable communications under difficult conditions of radio wave propagation is very urgent. In the field of telecommunications, multiposition types of modulation are widely used, which, despite their good spectral characteristics, provide low noise immunity under conditions of nonfluctuating interference, especially in cases of retransmitted interference. Therefore, it is relevant to explore the possibility of using multiple frequency-shift keying (M-FSK) signals in radio systems with complex interference environments. The paper sets out to analyze the noise immunity of coherent reception of M-FSK signals against the background of retransmitted interference.Methods. Statistical radio engineering and mathematical modeling methods are used according to the theory of optimal signal reception.Results. A model of the M-FSK signal and retransmitted interference is provided. The statistical parameters of the distributions of random processes occurring in a multichannel coherent receiver of M-FSK signals against retransmitted interference are obtained; based on this, the bit error rate is calculated when receiving M-FSK signals of different positionality M against retransmitted interference with different intensities.Conclusions. The impact of retransmitted interference is shown to result in a decrease in the noise immunity of M-FSK signal reception, which is greater the higher its intensity. With increasing positionality of M-FSK signals at low intensity of retransmitted interference, the noise immunity of reception is significantly improved; however, high-intensity interference significantly increases the bit error rate. The presence of interference with a relative intensity of 0.5 causes energy losses from 4 to 6 dB depending on the positionality. When M > 4, M-FSK signals gain significantly in terms of noise immunity over signals with multiple phase-shift keying, quadrature amplitude modulation, and amplitude and phase-shift keying.

Objectives . An urgent task in the context of modern radio and television systems is to improve the quality and quantity of transmitted information. For example, the use of multiple amplitude-phase shift keyed (APSK) signals—16-APSK and 32-APSK—in digital satellite television systems of the Digital Video Broadcasting-Satellite2 (DVB-S2) standard made it possible to transmit 30% more data in the same frequency bands in comparison with the previous DVB-S standard. Such increases in information transmission rates impose more stringent requirements on hardware. An important role in the reception of APSK signals, as well as the signals of other coherent signal processing systems, is played by the stability of synchronization systems. The presence of operational errors can significantly reduce the quality of information reception. The aim of the present work was to analyze the effect of phase and clock synchronization errors on the reception noise immunity of APSK signals with a ring signal constellation structure. Methods . The study used statistical radio engineering methods informed by optimal signal reception theory. Results . The effect of phase and clock synchronization errors on the reception noise immunity of APSK signals having a signal constellation ring structure is analyzed. The dependencies of the bit error probability on the magnitude of the phase shift and the clock offset were characterized. The effect of synchronization errors on reception quality were compared with the known results for quadrature amplitude modulation (QAM) signals. Conclusions . At an acceptable energy loss of no more than 1 dB, the critical phase error can be considered as 2°-3°, while the critical clock error is 3-4%. A coherent receiver of APSK signals is more sensitive to the phase error of reference oscillations than a similar receiver of QAM signals, whereas clock errors have the same effect on the reception quality of these signals.

Objectives . Analysis of the reception noise immunity of multiple phase shift keying (M-PSK) and quadrature amplitude modulation (M-QAM) signals has demonstrated a significant reduction in the quality of reception of discrete information due to the presence of various types of non-fluctuating interference in a radio communication channel including targeted harmonic interference. Therefore, the development of algorithms for compensating the influence of such forms of interference is an urgent task. While various methods for combatting this kind of interference, these vary in terms of their effectiveness. The aim of the present work is to synthesize and analyze the optimal algorithm for the reception of M-PSK and M-QAM signals with incoherent processing of harmonic interference. Methods . Various statistical radio engineering and computer simulation methods were used in accordance with optimal signal reception theory. Results . Synthesis and analysis of the optimal algorithm for receiving M-PSK and M-QAM signals with incoherent processing of harmonic interference were carried out. In addition to calculating the correlation integrals in the receiver, it is necessary to form weight coefficients, whose value depends on the correlation of the interference oscillation (extracted from the received mixture) with a sample of the interference stored in the receiver. The dependences of the bit error probability on the signal-to-noise ratio, interference detuning, and inaccuracy in setting the frequency and level of the interference sample in the receiver were obtained. It is shown that the higher the gain in the noise immunity of reception, the greater the intensity of the harmonic interference. Conclusions . The synthesized receiver circuit effectively compensates for harmonic interference. However, the efficiency of its operation depends on the detuning of the harmonic interference relative to the center frequency of the spectrum of the useful signal. The scheme for incoherent processing of harmonic interference remains operational even with small (within ±10%) inaccuracies in setting the frequency and the level of the interference copy in the receiver.

Objectives . Radio-technical information transmission systems are widely used in various sectors of our life, not only for telecommunications and associated domestic needs, but also for the functioning of various special services, such as emergency response units, which increasingly use robotic complexes in the course of their work. In the event of an emergency, robot devices can be used to get in under rubble, in concrete pipes or other municipal facilities, which typically result in a sharp deterioration of the necessary conditions for the propagation of radio waves. In this regard, the problem of ensuring reliable communication with the robotic complex becomes rather acute. The aim of the present work is to reduce the effect of multipath propagation of radio waves in the communication channel under complex interference conditions. Methods . The methods of statistical radio engineering and mathematical modeling are used according to optimal signal reception theory. Results . The presented model for a multi-element, spatially-distributed, in-phase receiving antenna of various configurations, featuring an electronically adjustable radiation pattern, is designed to ameliorate the multipath nature of signal propagation. A simulation of a multipath communication channel was carried out in the presence of one main and three reflected beams of radio wave propagation, as well as with harmonic interference at two angles of its arrival and different frequency detuning relative to the frequency of the useful signal. The probability of a bit error when receiving discrete information using the proposed antenna is estimated. Conclusions . The proposed signal processing algorithm on the receiving side can be used to partially compensate for the influence of the multipath effect. As a result, the noise immunity of information reception in comparison with reception on an omnidirectional antenna with one antenna element increases: for a bit error probability of 10 −3 , the energy gain ranges from 2 dB for two beams to 7–10 dB for three or four beams. In the presence of concentrated harmonic interference in the radio channel, its simultaneous spatial (by the antenna) and spectral (by the demodulator) filtering is also observed, the effectiveness of which depends on the direction of arrival and the frequency detuning of the interference, which also leads to a significant decrease in the error probability.

Objectives. Phase-shift keyed (PSK) signals are widely used in many telecommunication, communication, and cellular information transmission systems. Phase-shift keying provides a higher noise immunity than amplitude and frequency modulations do. An increase in the modulation order of such a signal leads not only to an increase in its spectral efficiency, but also to a certain decrease in the noise immunity of reception. To ensure a high noise immunity of reception of multiple phase-shift keyed (MPSK) signals, a demodulator should provide the coherence of the reference oscillation with the carrier. Ignorance of the frequency and phase of the received signal leads to significant energy losses. The purpose of this work was to synthesize and analyze algorithms for receiving MPSK signals with phase fluctuations caused by changes in the carrier frequency due to the Doppler effect against the background of white Gaussian noise.Methods. The problem was solved using the apparatus of optimal nonlinear filtering and methods of statistical radio engineering.Results. A demodulator was synthesized, which includes two interconnected units. One of them is a discrete symbol estimation unit, at the output of which a decision on the received symbol is issued, and the other is a phase-lock circuit. Analytical expressions were derived to estimate the characteristics of the receiver noise immunity as functions of the signalto-noise ratio and fluctuation parameters. It was shown that the synthesized quasi-coherent algorithm compensates well for the MPSK signal phase fluctuations caused by the instability of the master oscillator and the Doppler effect.Conclusions. Comparison of the results of this work with results obtained in the case of the absence of fluctuations in the initial phase showed that, at a high relative speed of the transmitter and the receiver (satellite radio channel), the energy loss is no more than 1 dB, and at lower speeds of the objects, it is about 0.2 dB and less.

Signals with quadrature amplitude modulation (QAM) is widely used for high-speed transmission of information in many radio systems and, in particular, in digital television systems. In the receiver, which is part of the transceiver equipment of such systems, there is a block for the formation of reference oscillations and a clock synchronization block. Due to hardware instabilities and propagation conditions, phase and clock errors may occur, which cause additional errors during demodulation of the received signal, and which can significantly impair the noise immunity of the reception. The paper investigates the effect of phase and clock synchronization errors on the noise immunity of coherent reception of QAM signals. Using the methods of statistical radio engineering, the parameters of the distributions of processes in the receiver are obtained and the probability of bit error is estimated. The dependences of the probability of bit error on the magnitude of the phase error in the formation of the reference oscillations and on the relative displacement of the clock moments, as well as on the signal-to-noise ratio, are obtained. It is shown that these errors can greatly reduce the noise immunity of the reception, and with an increase in the positioning of the signals, this effect increases. If we assume that the admissible reception energy loss is 0.5 dB due to each of these errors, then the allowable phase error is from ~3° at M = 4 to ~1° at M = 64, and the allowable clock synchronization error, respectively, is from ~5% at M = 4 to ~2% at M = 64. To provide more stringent requirements for the magnitude of losses, the requirements for the indicated errors increase significantly.

Quadrature amplitude modulation (QAM) signals are widely used in modern information transmission systems. The quality of the receiver of such signals is significantly reduced if non-fluctuation interference is present in the communication channel. Narrow-band (harmonic) interference with the frequency of the useful signal is especially dangerous. The aim of this work is to develop and study an adaptive algorithm for suppressing such interference when receiving QAM signals. The algorithm is based on a non-recursive digital filter with adjustable weights. It uses known information about the shape of the phase pulse of the signal. The efficiency of the algorithm is investigated by the method of computer simulation. When checking the performance of the algorithm, the spectrum of the signal and noise, the amplitude-frequency characteristic of the adaptive filter and the change in its shape over time were estimated. For 4-QAM and 16-QAM signals, the dependences of the bit error probability on the intensity of harmonic interference and on the signal-to-noise ratio are obtained. It is shown that the adaptive filter effectively suppresses harmonic interference with a relative intensity µ> 0.2 when receiving a 4-QAM signal. The energy advantage is 2 dB or more. When receiving QAM signals with M ≥16, which also have amplitude modulation, the algorithm remains operational, but the efficiency of using this adaptive filter is much lower. The energy advantage does not exceed 0.5 dB.

Objectives. The widespread use of radio data transmission systems using signals with multiposition phase shift keying (MPSK) is due to their high noise immunity and the simplicity of constructing the transmitting and receiving parts of the equipment. The conducted studies have shown that the presence of non-fluctuation interference, in particular, harmonic interference, in the radio channel significantly reduces the noise immunity of receiving discrete information. The energy loss in this case, depending on the interference intensity, can range from fractions of dB to 10 db or more. Therefore, interference suppression is an important task for such radio systems. The aim of the work is to synthesize and analyze an algorithm for optimal nonlinear filtering of MPSK signals against a background of harmonic interference with a random initial phase.Methods. The provisions of the theory of optimal nonlinear signal filtering and methods of statistical radio engineering are used.Results. The synthesis and analysis of the algorithm of optimal nonlinear filtering of MPSK signals against the background of harmonic interference with a random initial phase are carried out. The synthesized receiver contains a discrete symbol evaluation unit, two phase-locked frequency circuits of reference generators that form evaluation copies of the signal and interference, and cross-links between them. Analytical expressions are obtained that allow calculating the dependences of the bit error probability on the signal-to-noise ratio and the interference intensity µ. It is established that uncompensated fluctuations of the initial phase of the useful signal have a greater effect on the receiver noise immunity than similar fluctuations of the phase of harmonic interference, especially with low positional signals.Conclusions. Comparison of the obtained results with the results obtained in the case when there are no harmonic interference compensation circuits shows that the use of the obtained phase filtering algorithms allows for almost complete suppression of harmonic interference. Thus, if µ = 0.5 and the probability of error is 10−2, the energy gain at M = 2 is about 2.5 dB, at M = 4 – about 6 dB, at M = 8 and M = 16 – at least 10 dB.

For the first time, a passive method for radiosensor diagnostics of the integrity of signals from microprocessor devices was developed and presented. The method is based on the registration of the electrical component of the near field of electromagnetic radiation induced as a result of the clock formation (variability) of the impulse response of a digital circuit caused by the dynamic restructuring of the active configuration of its in-circuit and peripheral architecture. It is shown that real radiation is a superposition of fields of emitters of the active architecture of a microprocessor, each of which has its own impulse and amplitude-frequency characteristics with its own peaks and dips, resonances and excitations. An expression of the free component is presented for the oscillatory nature of the process of energy redistribution between reactive storage devices, which depends on the capacitances of the gate dielectrics of MIS transistors, barrier and diffusion capacities of p-n junctions, inductances and ohmic resistances of circuit elements and the scheme of their architectural connection. An experiment was prepared and carried out on the method of passive radio-wave technical diagnostics of microprocessor devices on a specially developed test sample with a known command execution algorithm. The results of registration of a series of signal radio profiles when starting a sample of a digital device are presented, and a correlation assessment of the reproducibility of the experiment is carried out. It is proved that time interval transitions of free oscillations are formed on the reference signal radio profile. These transitions correspond to the microcontroller’s reference to the periphery according to the algorithm of the command functioning of the sample. The possibility of obtaining detailed information about the nature of the peripheral load and its performance by examining the corresponding sections of the reference signal radio profile is shown. It was found that the spectral-time frames of the software and hardware functioning of the digital device under study are clearly identified on the recorded radio images.

Quadrature amplitude modulation (QAM) is used for high-speed information transmission in many radio systems and, in particular, in DVB-S and DVB-S2/S2X digital satellite television systems. A receiver included as a part of the transmitting equipment of such systems has a block for the formation of quadrature oscillations used as a reference for signal demodulation. Due to hardware instabilities, amplitude and phase errors may occur, which leads to quadratures imbalance. These inaccuracies cause additional errors in the received signal demodulation. This can significantly degrade the noise immunity of the reception. The paper investigates the influence of amplitude and phase errors in the formation of quadrature oscillations (imbalance of quadratures) on the noise immunity of coherent reception of QAM signals. Using the methods of statistical radio engineering the parameters of the distributions of processes in the receiver are obtained, and the probability of a bit error is estimated. The dependences of the bit error probability on the amplitude unbalance factor, on the phase error of quadrature formation and on signal-to-noise ratio are obtained. It is shown that the amplitude imbalance of the quadratures leads to a significant decrease in the noise immunity of QAM signals reception at M ≥ 16. The acceptable amplitude deviation in this case can be considered to be equal to 5%. At M= 4, the amplitude imbalance in a wide range of values practically does not affect the noise immunity. The phase imbalance of quadratures markedly affects the noise immunity of coherent reception of QAM signals. The permissible phase error is no more than 0.05 rad (3 degrees). As the signals positionality increases, this influence also increases.

The development of television technologies and the need to transmit high-quality video information requires that modern digital television and broadcasting systems can transmit large amounts of information. The use of signals with multi-position amplitude and phase-shift keying 16-APSK and 32-APSK in DVB-S2 generation satellite television systems made it possible to transmit 30% more data in the same frequency bands compared to the previous DVB-S standard. The latest DVB-S2X digital satellite TV standard is an extension of the DVB-S2 standard and supports modulations of 64,128,256-APSK. It is known that increasing the positionality of signals reduces the noise immunity of their reception and the system as a whole. In addition, the presence of non-fluctuation interference in the radio channel that falls into the frequency band of the useful signal has a strong influence on noise immunity. The article uses statistical radio engineering methods to calculate the probability of a bit error when receiving M-APSK signals against the background of phase-shift keying interference at different parameters of the latter. It is shown that of phase-shift keying interference of even low intensity (µ < 0.3) falling into the main lobe of the signal spectrum significantly reduces the noise immunity of receiving 16-APSK and 32-APSK signals. High-intensity interference (µ ≥ 0.5) practically destroys reception. The influence of phase-shift keying interference decreases with an increase in its detuning relative to the carrier frequency of the useful signal and an increase in the relative transmission rate of the interference. A comparison of the reception quality when using M-PSK, M-QAM and M-APSK signals is carried out and it is shown that the noise immunity of receiving M-QAM and M-APSK against the background of phase-shift keying interference is approximately the same. M-PSK signals are significantly inferior to them in terms of reception noise immunity.

The purpose of the work is a comparative analysis of the influence of synchronization errors, namely, the errors of the carrier phase estimation and the errors of the clock synchronization system on the noise immunity of coherent receiving of signals with multi-position phase-shift keying and quadrature amplitude modulation. Using the method of statistical radio engineering, analytical expressions are obtained that allow calculating the probabilities of a bit error with static errors in estimating the phase and clock moments. It was shown that the inaccuracy in the estimation of these parameters strongly affected the noise immunity of the coherent receiving of multi-position phase-shift keying and quadrature amplitude modulation signals; with an increase in the positioning of the signals, this effect increases, and it is more pronounced for a multi-position phase-shift keying receiver. The permissible errors in estimating the phase of the carrier and clock moments for signals of different positioning are determined.

The energy and spectral advantages of signals with phase-shift keying predetermined their widespread use in modern digital navigation, communications and television systems. The use of this type of signal in a multi-position format with an increased number of possible phase states allows increasing the information capacity of the channel signal, and consequently the throughput rate of radio channels. The presence of non-fluctuation interference in such radio channels greatly reduces the noise immunity of information reception. A well-known way to deal with such interference is to use adaptive non-recursive filters in the receiver. The article evaluates the effectiveness of using such a filter with an algorithm for setting weight coefficients that controls the constant envelope of a useful signal when receiving signals with multi-position phase shift keying against the background of noise and non-fluctuation interference. Two types of such interference are considered – harmonic and relayed. Using computer simulation, the optimal filter parameters (adaptation coefficient and its length) are determined; the effect of the filter on the noise immunity of the quadrature signal receiver with multi-position phase shift keying for various combinations of interference and their intensity is estimated. It is shown that such an adaptive filter can successfully cope with the most dangerous sighting harmonic interference.

The paper considers the efficiency of an adaptive non-recursive filter using the adjustment algorithm for weighting coefficients taking into account the constant envelope of the desired signal when receiving signals with multi-position phase shift keying against the background of noise and non-fluctuation interference. Two types of such interference are considered - harmonic and retranslated. The optimal filter parameters (adaptation coefficient and length) are determined by using simulation; the effect of the filter on the noise immunity of a quadrature coherent signal receiver with multi-position phase shift keying for different combinations of interference and their intensity is estimated. It is shown that such an adaptive filter can successfully deal with the most dangerous sighting harmonic interference.

The wide spread of various radio systems with phase shift keying, including multi-position (MPSK), is due to their high noise immunity and ease of construction of the transmitting and receiving parts of the equipment. In real equipment, additional differential (relative) encoding is used when implementing transmitter and receiver circuits and, accordingly, DMPSK signals are used. One of the ways to receive such signals is to use an autocorrelation demodulator built on a quadrature scheme. The paper studies the noise immunity of an autocorrelation demodulator of signals with differential phase shift keying in the presence of Gaussian noise, Rayleigh fades and harmonic interference in the radio channel. The statistical parameters of signals and interference in the inphase and quadrature channels of the autocorrelation demodulator are determined. For M = 2 and 4, analytical formulas are obtained for the probability of a symbolic error, conditional on the random phase of harmonic. It is verified that the formula at M = 2 without harmonic interference reduces to an expression known from the literature. The values of the unconditional probabilities of symbolic errors are obtained by numerical averaging. It is shown that at a low level of harmonic interference, Rayleigh fading has a dominant effect. With a large level of interference, the additional energy loss can be several decibels, and at M = 4 these losses are significantly greater than at M = 2.

The article defines large territorially distributed automated systems, which include systems that collect and process information from spatially spaced sensors on objects. Examples of such automated systems are military systems, such as a missile attack warning system, a space control system, strategic and non-strategic missile defense systems, and civil systems, such as the state automated Control system, the air traffic control system and other systems. The purpose of these systems is the continuous monitoring of the state of a set of certain objects, the environment of their functioning, the constant assessment of the parameters of objects, the identification of dangerous situations in the behavior of objects and the environment, as well as the development of measures to reduce the level of possible security threats and eliminate dangerous situations.The typical structure of large territorially distributed automated systems includes sources and consumers of information, telecommunication facilities, as well as a center for processing input data and preparing information for consumers. The sources of information are operators, technical means of observation and specialized measuring instruments. Telecommunication means of big territorially distributed automated systems are formed in two ways. The first option uses existing global data net-works. In the second variant, self-made data transmission networks are formed on the basis of specially created means of data transmission and the use of dedicated data channels. The center of input data processing and information preparation contains a complex of automation tools and personnel providing maintenance, repair and operation.The functions and the most significant hardware and software components of large territorially distributed automated systems are presented. The main indicators of quality of their functioning and stages of life cycle are characterized: development of requirements, creation of a prototype, certification, mass production, operation, modernization, the end of operation and utilization.

The paper presents the noise immunity analysis of coherent and autocorrelation signal demodulators with multiple phase shift keying in the radio channel in the presence of noise, harmonic and retranslated interference using simulation modeling. A comparison of the results is shown. The energy loss of the autocorrelation demodulator is defined and the effect of the noise intensity on the error bit rate value is estimated.

Using statistical radioengineering methods, we analyzed the noise immunity of the receiving of the signals with multiposition quadrature amplitude modulation (M-QAM) in the presence of noise and relayed interference in the radio channel. It is shown that the reception quality of signals with M-QAM is susceptible to the influence of such interference, and this effect increases as the positioning of the signals increases. It is also established that the noise immunity for the reception of M-QAM signals is significantly better against the background of relayed interference than that of similarly positioned M-PSK signals.